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/* $Id: pid.c,v 1.1 2003/08/08 08:05:23 reinelt Exp $
*
* PID file handling
*
* Copyright 1999, 2000 by Michael Reinelt (reinelt@eunet.at)
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2, or (at your option)
* any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
*
* $Log: pid.c,v $
* Revision 1.1 2003/08/08 08:05:23 reinelt
* added PID file handling
*
*/
/*
* exported functions:
*
* int pid_init (const char *pidfile)
* returns 0 if PID file could be successfully created
* returns PID of an already running process
* returns -1 in case of an error
* int pid_exit (const char *pidfile)
* returns 0 if PID file could be successfully deleted
* otherwise returns error from unlink() call
*
*/
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/stat.h>
#include "debug.h"
#include "pid.h"
int pid_init (const char *pidfile)
{
char tmpfile[256];
char buffer[16];
int fd, len, pid;
snprintf(tmpfile, sizeof(tmpfile), "%s.%s", pidfile, "XXXXXX");
if ((fd=mkstemp(tmpfile))==-1) {
error ("mkstemp(%s) failed: %s", tmpfile, strerror(errno));
return -1;
}
if (fchmod(fd,S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH)==-1) {
error ("fchmod(%s) failed: %s", tmpfile, strerror(errno));
close(fd);
unlink(tmpfile);
return -1;
}
snprintf (buffer, sizeof(buffer), "%d\n", (int)getpid());
if (write(fd, buffer, strlen(buffer))!=strlen(buffer)) {
error ("write(%s) failed: %s", tmpfile, strerror(errno));
close(fd);
unlink(tmpfile);
return -1;
}
close (fd);
while (link(tmpfile, pidfile)==-1) {
if (errno!=EEXIST) {
error ("link(%s, %s) failed: %s", tmpfile, pidfile, strerror(errno));
unlink(tmpfile);
return -1;
}
if ((fd=open(pidfile, O_RDONLY))==-1) {
if (errno==ENOENT) continue; // pidfile disappared
error ("open(%s) failed: %s", pidfile, strerror(errno));
unlink (tmpfile);
return -1;
}
len=read(fd, buffer, sizeof(buffer)-1);
if (len<0) {
error ("read(%s) failed: %s", pidfile, strerror(errno));
unlink (tmpfile);
return -1;
}
buffer[len]='\0';
if (sscanf(buffer, "%d", &pid)!=1 || pid==0) {
error ("scan(%s) failed.", pidfile);
unlink (tmpfile);
return -1;
}
if (pid==getpid()) {
error ("%s already locked by us. uh-oh...", pidfile);
unlink(tmpfile);
return 0;
}
if ((kill(pid, 0)==-1) && errno==ESRCH) {
error ("removing stale PID file %s", pidfile);
if (unlink(pidfile)==-1 && errno!=ENOENT) {
error ("unlink(%s) failed: %s", pidfile, strerror(errno));
unlink(tmpfile);
return pid;
}
continue;
}
unlink (tmpfile);
return pid;
}
unlink (tmpfile);
return 0;
}
int pid_exit (const char *pidfile)
{
return unlink(pidfile);
}
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